To me it seems like the Change module should get some attention.
We use this module a lot, but I see the following problems with it:
You can edit a change after approval
Thats right, if an agent creates a change and the CAB board approves it, the agent can edit the change and the CAB board will not be informed or have to approve the edit - the change remains approved
Changes stay open after approval
If I filter changes on Approved and Open right now in our solution, I get 210 changes. These changes should be status=Closed and I cannot bulk change these - this is only possible with tickets.
These are major issues for us.
We do understand your problem where you don't want an agent to modify the Change once it is sent for approval. We have received similar requests from few other customers as well and my team is analyzing this to see if this can be solved by bringing Change Manager role or enhancing the current roles and scope.
I will create a Support Ticket and will have this passed to our Product team and will keep you posted on further updates.
Also, we will work with our Developers and would let you know if we can achieve this workflow through a Custom app.
Regarding Bulk action for Changes, this seems to be an important request and will definitely talk to my Team about the same and will keep you informed.
As a workaround maybe, we can use API and update all the open Tickets after Approval which we'll be happy to help you.
Will email you on the ticket to assist you further.